High-Density Formation of Ir/MoOx Interface through Hybrid Clustering for Chemoselective Nitrostyrene Hydrogenation

Abstract

To form high-density metal/oxide interfacial active sites, we developed a catalyst preparation method based on hybrid clustering. An iridium–molybdenum (Ir–Mo) hybrid clustering catalyst was prepared by using the hybrid cluster [(IrCp*)₄Mo₄O₁₆] (Cp* = η⁵-C₅Me₅) as the precursor. The Ir–Mo hybrid clustering catalyst selectively reduced the nitro group in the hydrogenation of 4-nitrostyrene, whereas the coimpregnated Ir–Mo catalyst reduced both the nitro and vinyl groups nonselectively. The hybrid clustering catalyst also exhibited high selectivity, even at a high Ir loading (5 wt %), in contrast to Ir/MoO₃, which exhibited high selectivity only at low Ir loadings (<0.3 wt %). In situ X-ray absorption spectroscopy analysis revealed that oxygen vacancies were formed at the Ir/MoO_x interface in the presence of H₂. We concluded that a high-density Ir/MoO_x interface contributes to the preferential adsorption of nitro groups on vacant sites, promoting the selective hydrogenation of nitro groups.